This is not actually a module, but an include file to use in hook_update_N() calls. The file contains helper functions for common update tasks, such as renaming variables, installing and reverting features, granting and revoking permissions, deleting and altering CCK fields, changing content type information like Title label, etc.
Typically, each hook_update_N() function returns an array with the results of the calls to
update_sql(). Every function in update_api works in much the same way, passing by reference the
$ret array as an argument and reporting each update and error encountered. While
update_sql() is very useful for module level update sequences, maintaining updates on a site level (in an install profile wrapper module, say) between dev/staging/production workflow states becomes tedious with only that one tool in the toolbox. The API provided here hopes to expand your toolset in maintaining site updates, offering functions for common update tasks and more complex scenarios.
Currently, this API needs much love in the area of commenting and docblocks. I apologize in advance. Please comment away and create patches!
I would love to get a few more maintainers on this, so if you're interested please contact me.